The present invention relates to a diazotype copying apparatus of the kind which employs a fume-producing chemical developing agent, e.g. ammonia, and particularly to a mechanism for dealing with the problem of fumes produced by equipment of this sort.
The gathering of fume contaminated air from such development equipment and passing it through a treatment chamber which contains material with absorbent and/or reagent properties for preventing most of the fumes from passing into the ambient atmosphere is a well known procedure as shown in U.S. Pat. Nos. 3,679,369, 4,059,409 and 4,167,319.
Presently used equipment performs this function successfully, but is characterized by the requirement of a rather complex and expensive adjunct to the copying machine for the sole purpose of rendering the fumes innocuous. Moreover the detection of the appropriate time to change the active ingredients in the treatment chamber offers a problem, and, as presently constructed the job of recharging the treatment chamber with fresh material is one which is either rather awkward and unpleasant for the operator to perform or at best requires the replacement of a filter cartridge of expensive construction.